Within a telecommunications network, a switching system or other type of switching node couples originating and terminating stations for a call. Typically, first and second software modules, commonly referred to as an originating call handler and a terminating call handler, respectively, residing within the switching node handles exchanges of messages with a software agency respectively residing at the originating and terminating stations. Alternately, the originating and terminating stations may be terminals where the call actually originates/terminates or a trunk which couples the switching node to a next switching node. In either configuration, however, to complete a call involves a series of exchanges--from the originating agency to the originating call handler, from the originating call handler to the terminating call handler and from the terminating call handler to the terminating agency. For an agency and a handler to exchange messages therebetween, both must format messages destined for the other in accordance with a common protocol. Thus, completing a call becomes quite complex if the originating and terminating agencies use different protocols.
In recent years, several solutions to this problem have been proposed. One proposed solution has been to provide a single handler which conducts exchanges with both the originating and terminating agencies. To create such a handler, however, requires explicit knowledge of both the originating and terminating access links. While the resultant handler is able to rapidly conduct exchanges, continued maintenance thereof becomes a difficult task. For example, since the various agencies are coupled together by the single handler, a software update to one agency may require updates to all of the agencies which interact with the updated agency by way of the single handler.
Another proposed solution has been to maintain separation of the originating and terminating call handlers but to provide a generic protocol by which the two handlers may communicate. Notwithstanding the difficulties in developing a generic protocol acceptable throughout the industry, the use of a generic protocols is often typified by the need to constantly revise the protocol due to changes to the access protocols to which it provides an interface. Moreover, a generic protocol is inefficient in that it always requires conversions at both the originating and terminating ends.